1. Field of the Invention
The present invention relates to electrical connector technology and more particularly, to an electrical connector for flexible printed circuit board application, which effectively reduces high frequency interference.
2. Description of the Related Art
Following fast development of computer, network and electronic information technologies, various advanced electronic devices and systems are well developed and widely used for different applications. Further, it is the market trend to create electronic devices having light, thin, short and small characteristics. In consequence, circuit board electronic components must be made extremely strong, small and precise. Further, many different electrical connectors may be used in an electronic apparatus to connect different components and parts to a circuit board for signal transmission. Designing an electrical connector for signal transmission must consider the factors of signal transmission capacity and body size miniaturization. Electrical connectors for FPC (Flexible Printed Circuit) application are then created. Electrical connectors for FPC application have the characteristics of a large number of conducting terminals and low profile. These electrical connectors are intensively used in computers and related peripheral equipment for high frequency signal transmission. However, because these electrical connectors have a high pin count, interferences (statistical interference, electromagnetic interference, impedance matching, noise interference, cross-talk interference) may occur during transmission of a high frequency signal if the pins (conducting terminals) are curved.
Taiwan Patent Number: M304148 discloses an electrical connector entitled “Electrical Connector for Flexible Printed Circuit Board”. According to this design, as shown in FIGS. 7-9, a press member C is inserted into a front opening A1 of a housing A to let top arms B1 and bottom contact portions B2 of respective conducting terminals B be engaged into respective notches C3 of the press member C and positioned in the bottom side of the front opening A1 of the housing A respectively. At this time, rear bonding portions B3 of the conducting terminals B suspend outside the housing A for bonding to an external mainboard, and respective positioning points C4 in the notches C3 of the press member C are respectively positioned in respective bottom grooves B11 of the top arms B1 of respective conducting terminals B. Thereafter, support members D are respectively inserted into respective mounting portions A2 of the housing A to support respective support arms C2 of the press member C, holding down the positioning points C4 of the press member C in the bottom grooves B11 of the respective conducting terminals B. At this time, press portions C5 of the press member C are kept between the top arms B1 and bottom contact portions B2 of the conducting terminals B. Thus, the press member C can be turned relative to the housing A between an open position and a close position and will not fall out of the housing A.
When connecting the electrical connector to a flexible printed circuit board E, attach the support arms C2 of the press member C to the respective support members D, and then move an operating portion C1 of the press member C to bias smoothly arched surfaces C21 of the support arms C2 relative to the respective support members D from horizontal to vertical while keeping the positioning points C4 of the press member C in the bottom grooves B11 of the respective conducting terminals B, and then insert the flexible printed circuit board E into the gap between the top arms B1 and bottom contact portions B2 of the conducting terminals B, and then turn the press member C backwardly from vertical to horizontal to force the press portions C5 of the press member C against the flexible printed circuit board E, enabling the flexible printed circuit board E to be clamped between the press portions C5 of the press member C and respective protrusions B21 of the bottom contact portions B2 of the conducting terminals B. Thus, the flexible printed circuit board E and the conducting terminals B are electrically conducted. Subject to the design of the smoothly arched surfaces C21 of the support arms C2, the press member C can be smoothly biased relative to the respective support members D between the horizontal close position and the vertical open position. Further, by means of using the support members D to support the support arms C2 of the press member C, the positioning points C4 of the press member C are positively kept in the bottom grooves B11 of the respective conducting terminals B.
However, according to the aforesaid prior art design, the conducting terminals B have a roughly C-shaped profile where the top arms B1 respectively extend from the respective bottom contact portions B2 of the conducting terminals B without contacting the flexible printed circuit board E. During application, high frequency signal is transmitted through the flexible printed circuit board E and the bottom contact portions B2 and bonding portions B3 of the conducting terminals B to the mainboard. The branched top arms B1 tend to cause a skin effect, limiting the cross-sectional conducting terminal area available to carry alternating current, increasing the resistance of the conducting terminals above the normal resistance for direct current. In consequence, signal transmission bandwidth and quality may not reach the designed standards, affecting normal functioning of the electronic device (computer or network equipment).
Therefore, it is desirable to provide an electrical connector for high frequency application that eliminates the aforesaid problems.